<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    /* .box {
      width: 50vw;
      height: 30vw;
      background-color: pink;
    } */

    .box {
      width: 50vh;
      height: 30vh;
      background-color: green;
    }
  </style>
</head>
<body>
  <div class="box"></div>
</body>
</html>